The present invention relates to organic laminate substrates and, more particularly, relates to organic laminate substrates which have been modified to alleviate certain stresses which may cause out-of-plane warpage during thermal excursions.
Organic laminate substrates, due to the nature of functional electrical designs, are fabricated with materials properties gradients from center to periphery and from top to bottom in the chipsite area. These materials properties gradients, primarily in coefficient of thermal expansion and Young's modulus, drive radial stresses during heating and cooling. Reactive hoop stresses oppose these radial stresses. Both these radial stresses and reactive hoop stresses are relieved by out of plane warpage during thermal excursions. Out of plane warpage can cause problems, such as shorts and opens in semiconductor chip joining, as well as similar difficulties in module and assembly fabrication. Industry solutions may be design restrictions, which can limit function of the organic laminate substrate, and fixturing during manufacturing, which may be expensive.